1. Field of the Invention
The invention relates to pneumatic splinting devices, particularly those used for the management of post-operative edema associated with the amputation of a human extremity, such as the leg, and those used to assist the early post-operative ambulation of an amputee.
2. Description of the Prior Art
Pneumatic splints were heretofore fabricated by sealing the perimeter of two sheets of non porous, flexible material, thus forming inner and outer walls which could be wrapped around the human limb to which the splint was to be applied and then the chamber defined between the inner and outer walls was filled with low pressure air to immobilize the device and the enclosed limb.
While this construction is adequate for use as a short term emergency splint to immobilize fractures occuring in the extremities, it has pronounced disadvantages when an attempt is made to employ the device for a longer period of time, as required in the post amputation management of edema and early ambulation of the amputee. The two layer construction, when applied to a human limb or extremity and inflated by air, tends to mishape and apply non-uniform pressure to the surrounded limb, which results in a reduction of effective edema control and reduces the protective cushioning effect of the surrounding envelope formed by the inflated device. Since the expansion of the outer layer is limited solely by the tensile strength of the material, any non-uniformity in such tensile strength results in excessive localized expansion and reduced rigidity of the inflated device, which in turn reduces the supportive action of the device and hence its effectiveness as a ambulatory aid. Lastly, conventional pneumatic splints formed of two peripherally sealed layers normally result in the formation of a gap or channel running the length of the device in the area where the fastening means are attached to the device which hold the device in its annular configuration. This channel of reduced inflation forms an area into which the limb extremity is forced by the greater inflation of the remainder of the device, thereby resulting in that portion of the limb extremity being both unsupported and relatively uncushioned by the device.
Typical prior art pneumatic splints formed by the peripheral bonding of two layers of nonpervious material are disclosed in U.S. Pat. Nos. 2,823,668, 3,824,992 and 4,156,425.